no powerband, is it bad?

By vinny2k4o, Posted July 12, 2011

hi, my friend has an 03 125sx that he doesnt want so hes selling it, i kinda want to buy it but theres possibly a problem, it wont reach peak rpms/doesnt hit powerband(thas why he doesnt want it), is that bad (i know that means it isnt working proporly what i meant was how bad)

basically what i want to know is...

1.how bad is this for track and trails (will i stall, get stuck easier, have trouble with sand/mud, and or struggle with hill climbs)

2.is it just consistant power flow like a 4 stroke or will it be harder to start, take off, or go fast?

3.is it possible to/how much would it cost to fix this?

4.will it be bad for trails with larger rocks and small logs (i dont normally ride 2 strokes and when i do i go though gears so i honestly dont know the difference between having it and not)

5.basically, is it as rideable? will it work fine as long as i go though gears?

6.do you think i should buy it? he already put 700 into it and ive seen the receits for all the work he did to it too, hes been riding it on trails abit too, hes been riding two strokes forever though and loves powerband thus hes getting rid of it

7.i ride track sometimes, will it be ok for jumps?

By 01cr80, Posted July 12, 2011

it either needs to be jetted, have carb cleaned, right crank seal, or new top end. None are serious problems at all and should not stop you from buying it. That bike should be a rocket when its running right. You should put a top in anyway even if thats not the problem. How much were you going to buy it for?

By Lelandjt, Posted July 12, 2011

Sounds like too much of a basket case for an inexperienced mechanic. If you don't know how the engine works, buying one that's not working right sounds like a bad idea.

By vinny2k4o, Posted July 12, 2011

@lelandjt im actually not that bad, also wer all pretty good with motors or atleast my group is, one of my closer buds is in diesel tech,and @01cr80 if its a problem that simple then i can take it for 1350-1400 and fix it myself, but will it significantly effect my ability to keep up with the other 125/250fs on the trails if i dont fix it? (i probly wont fix it RIGHT away but ill check it out in a bit)

By gmoss357, Posted July 12, 2011

It is likely just the PV. IF he has had the jug off, he likely didn't get the PV hooked up right. OR, the PV system is all gummed up and not operating properly.

I have a pictorial in the FAQ sticky so you can see the PV assembly. The fork on the U shaped arm has to align with a rounded piece in the case when lowering the jug back down. It is easy to get wrong.

1. the 125 isn't a powerhouse with lots of bottom end, so it will be up to your skills on how well the bike does. Great bike to learn on, though.

2. It will have a typical 2 stroke hit, you can adjust that hit with the PV adjuster. Shouldn't be hard to start once jetted correctly.

3. May not cost you anything to fix it.

4. nope, that will depend on you.

5. lol, go thru the gears? It will be a little harder to ride than a bigger bore due to it's lacking low end, but it will still work.

6. can't say, haven't seen the bike, pictures, or know what he's asking...

7. The SX is a motocross bike.

By Mike in Fresno, Posted July 12, 2011

agree with G, Pv is first thing to check and easy to determine

By vinny2k4o, Posted July 12, 2011

It is likely just the PV. IF he has had the jug off, he likely didn't get the PV hooked up right. OR, the PV system is all gummed up and not operating properly.

I have a pictorial in the FAQ sticky so you can see the PV assembly. The fork on the U shaped arm has to align with a rounded piece in the case when lowering the jug back down. It is easy to get wrong.

1. the 125 isn't a powerhouse with lots of bottom end, so it will be up to your skills on how well the bike does. Great bike to learn on, though.

2. It will have a typical 2 stroke hit, you can adjust that hit with the PV adjuster. Shouldn't be hard to start once jetted correctly.

3. May not cost you anything to fix it.

4. nope, that will depend on you.

5. lol, go thru the gears? It will be a little harder to ride than a bigger bore due to it's lacking low end, but it will still work.

6. can't say, haven't seen the bike, pictures, or know what he's asking...

7.i meant can i ride it at the track fine (will not having powerband make it harder to hit the ramps/clear jumps

By Darrell41653, Posted July 12, 2011

Powerbands... I love it.

why is this subject so hard to understand?

A two stroke does NOT have any such magical device as a "powerband"

A four stroke does NOT have any such magical device as a "powerband"

The powerband is simply a word used to describe...I dont even want to get into it again.

Here is what to do bud. After ordering the blue powerband, pop the clutch cover off, wrap the powerband around the clutch basket, the other end wraps around the impeller of the water pump. Bolt everything back up, but before you start her up you will need to adjust the frequency of the muffler bearings. A powerband alone will not achieve maximum horsepower if it is not tuned to the muffler bearings. Remove the silencer, take out the packing, and inspect the bearings. On some older or well ridden bikes, these bearings may be worn out or completely missing. If this is the case, you will need to go to your local shop, remember to take along the serial number of the engine, and the silencer. They will need these to match up to the new bearings. Once you have the new ones in hand you can either try to attach them manually or what has worked best for me in the past is to remove the spark plug and drop the bearings directly onto the head, through the spark plug hole. Bolt everything back up, the start her up. Remember to "kick the powerband in" this will seat the bearings ....Let us know how this works for you...

By jimrick, Posted July 12, 2011

Where would one find a muffler bearing puller?Surely they aren't just set in the muffler or they would rattle causing the band to think the clutch is operating backwards thus making jumps at the track nearly impossible to photograph.

By Darrell41653, Posted July 12, 2011

Where would one find a muffler bearing puller?Surely they aren't just set in the muffler or they would rattle causing the band to think the clutch is operating backwards thus making jumps at the track nearly impossible to photograph.

By Greenisbest, Posted July 12, 2011

i tried it and it didnt work out well for me, now it needs a new cylinder. thanks alot.

By Darrell41653, Posted July 12, 2011

i tried it and it didnt work out well for me, now it needs a new cylinder. thanks alot.

Probably didnt have the correct size muffler bearings. That or you didnt "kick the powerband" in properly. On a two stroke the proper way to kick it in is thus... Crack the throttle about a quarter open, the chop the throttle suddenly, followed by a quick one half to three quarter opening of the throttle. A guy once told me that if you didnt kick the powerband in every time you ride the bike that it was bad for the muffler bearings.

By jimrick, Posted July 12, 2011

Good advice.I've almost got my plug hole dremeled out enough to fit the bearing but am wondering if I will be able to tap this new hole for a larger plug or would it be easier to just weld in a bung that matches the thread pitch and frequency of the original spark plug?I can't wait for mom to get off work as she knows more about this stuff than I do.

By Darrell41653, Posted July 12, 2011

Good advice.I've almost got my plug hole dremeled out enough to fit the bearing but am wondering if I will be able to tap this new hole for a larger plug or would it be easier to just weld in a bung that matches the thread pitch and frequency of the original spark plug?I can't wait for mom to get off work as she knows more about this stuff than I do.

Forget tapping it out. Just get some JB weld. Pack the JB Weld around the threads of the plug, then just stick the plug back in the hole. Works like a charm.

By jimrick, Posted July 12, 2011

My sister ate my last tube of hardener,but I do have a can of bondo that I used for my last head gasket,I just don't know if this color bondo is hi temp enough to accomodate the band contracting and expanding under a pre bearing load.That and I'm a little bit concerned about climate affecting the valve pins when approaching the starting gate.I've had to deal with that in the past and it is very embarrassing when the board gal laughs at me.

By Darrell41653, Posted July 12, 2011

My sister ate my last tube of hardener,but I do have a can of bondo that I used for my last head gasket,I just don't know if this color bondo is hi temp enough to accomodate the band contracting and expanding under a pre bearing load.That and I'm a little bit concerned about climate affecting the valve pins when approaching the starting gate.I've had to deal with that in the past and it is very embarrassing when the board gal laughs at me.

If your valve pins were coated with blue play dough you wouldnt have to worry about it.